The present invention relates to a power actuator embodying the type of mechanism per se taught and claimed in the instant inventor's previous U.S. Pat. No. 3,583,247 dated June 8, 1971, covering a "Power Actuator For Rotary Valves", and in particular is an improvement to provide in combination therewith a positive mechanical lock and hold function of the lost motion action by which operational adjustment and set of that mechanism is made when utilized in the highly specialized employment as a power actuator for remotely located high pressure and high volume flow control valves such as would be found in cooling system application for naval nuclear power plants and the like.
The continued use of quarter-turn full open-to-close fluid flow control devices such as ball, plug, and butterfly valves in both industrial and maritime applications in removed limited space locations requiring remote operation of a coupled power actuator to adjust the valve remains a much needed mechanical control function capability, as well as the need for highly compact and efficient power actuators that will hold and maintain the valve set once adjusted and not allow drift to a more open or closed position than that set to achieve the desired flow rate. It is through the incorporation of a circular rack and pinion timing gear assembly in combination with applicant's previously patented Power Actuator For Rotary Valves that provides the mechanical means whereby the power actuator lost motion movement after adjustment is positively arrested and there is no further movement thereof from vibration effects or fluid flow force effects, wherein the combination enables positive operational maintenance of valve set adjustment in the typical use application environment.
The applicant's previously cited power actuator device, in the use envisioned, was employed to convert rectilinear piston motion to rotary motion, however the device is equally adaptable for converting rotary motion to rectilinear motion. Another such device, although not suitable for quarter-turn high pressure valve set and control operations, is that as taught by Young in his U.S. Pat. No. 2,775,128 dated Dec. 25, 1956, which is for an apparatus to change rotary motion to rectilinear motion by means of a mechanical assembly somewhat similar functionally but structurally distinguished from that of applicant's previously Patented power actuator.
Additional teachings showing the use of circular rack and pinion timing gear means in lineal to rotary motion conversion devices and apparatus for purposes respectively of enhancing operational stability and control, for mechanical set and lock, and operational utilization in a valve operator of alternate mechanical function are as in turn respectively set forth in U.S. Pat. No. 2,166,975 to Sologaistoa dated July 25, 1939, in U.S. Pat. No. 2,754,687 to Brandon dated July 17, 1956, and in U.S. Pat. No. 4,186,613 to Carlson, Jr., dated Feb. 5, 1980.
Other linear to rotary motion converters of interest for operation and set of fluid control valves, but operable on mechanical assemblies and linkages distinguished from that utilized by applicant, are exemplified by the teachings respectively set forth in U.S. Pat. No. 3,709,106 to Shafer dated Jan. 9, 1973, in U.S. Pat. No. 4,133,215 to Norris et al dated Jan. 9, 1979, and in U.S. Pat. No. 4,504,038 to King dated Mar. 12, 1985.